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The Avatar Paradigm in Granular Materials


Kawamoto, Reid Yoshio (2018) The Avatar Paradigm in Granular Materials. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/4fr8-bn91.


Granular materials are ubiquitous in both everyday life and various engineering and industrial applications, ranging from breakfast cereal to sand to rice to medical pills. However, despite the familiarity of granular materials, their behavior is complex and efforts to characterize them are currently broad research areas in physics and engineering. Research of granular materials, as is the case with the research of other engineering materials such as rocks and metals, is beset with two gaps: the gap between reconciling macroscopic behavior with microscale (particle-scale, in the case of granular materials) behavior, and the gap between reconciling experimental and computational results. In this dissertation, we bridge these gaps through the "avatar paradigm." The avatar paradigm is a two-step process that numerically characterizes (from experimental images) and simulates the shapes and behavior of individual particles, which we call avatars. First, we validate that our avatars are indeed capable of faithfully capturing particle kinematics and interparticle contact, then apply the characterization process, level set imaging (LS-imaging), to two experimental specimens to compute particle kinematics and contact statistics. We then detail a computational method, the level set discrete element method (LS-DEM), that is able to simulate the behavior of avatars, and apply it (and LS-imaging) to two other experimental specimens, calibrating the model to one specimen and using the results to predict the behavior of the other, thus providing some reconciliation between experimental and computational results. Finally, we use the avatar process to characterize and simulate yet another experimental specimen, this time analyzing the results at length scales ranging from particle behavior to local behavior to macroscopic behavior, further validating the ability of the avatar paradigm to bridge experiments and computations and showing its power to reconcile different length scales.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Geomechanics, granular materials, discrete element method
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Mechanics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Andrade, Jose E.
Thesis Committee:
  • Bhattacharya, Kaushik (chair)
  • Asimaki, Domniki
  • Lapusta, Nadia
  • Andrade, Jose E.
Defense Date:2 June 2017
Record Number:CaltechTHESIS:06072018-230955387
Persistent URL:
Related URLs:
URLURL TypeDescription for ch. 2 for ch. 3 for ch. 4
Kawamoto, Reid Yoshio0000-0002-4936-5321
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11042
Deposited By: Reid Kawamoto
Deposited On:12 Jun 2018 19:57
Last Modified:28 Oct 2021 22:48

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